Electrical computers and digital processing systems: multicomput – Computer-to-computer data addressing
Reexamination Certificate
1999-02-01
2001-06-12
Lim, Krisna (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data addressing
C370S409000
Reexamination Certificate
active
06247062
ABSTRACT:
FIELD OF INVENTION
This invention relates to computer networks and more particularly to routing of control and data packets through a computer network
BACKGROUND OF THE INVENTION
For many years homes and businesses have utilized communication systems that enable fire and security system information to be transferred between remote sites (homes, businesses, etc.) and a security host monitoring station. Security companies such as Diebold, Wells Fargo, Brinks and ADT maintain large numbers of centralized monitoring stations that continually monitor security systems for subscribing customers. Each company uses a particular set of digitized codes or protocols, often simple number sequences, to determine the particular status of a security system. These protocols are typically proprietary to the particular security company.
FIG. 1
illustrates a security system monitoring arrangement according to the prior art. This patent will refer generally to protocols used by the ADT Company. However, the techniques described herein are applicable to a variety of companies employing various protocols, both for security systems and for other types of data transmission. As shown, customers at remote locations have respective alarm panels
100
and
102
. Each alarm panel
100
and
102
is connected to a respective bank of sensors
110
and
112
. In practice, each sensor bank
110
,
112
can comprise a large number of sensors, each having specialized functions, such as motion detectors, open-door switches, smoke detectors and the like. The sensors
110
and
112
communicate locally with the respective alarm panel
100
and
102
, providing security information to each panel.
The alarm panels each include conventional circuitry that translate sensor information into digital status signals. A modem
120
and
122
is provided in each respective panel. This modem, or an equivalent telephone communication device, interconnects the panel with the Public Switched Telephone System (PSTN)
130
. A dedicated telephone line can be used to provide a continuous connection for the panel. Alternatively, each modem can include appropriate answering functions and dialing functions to allow periodic calls to be placed by the panel over the PSTN and for receiving calls over the PSTN when the panel senses a ring signal.
The security company, at its monitoring site, maintains a hosts computer or other monitoring devices
140
. The host computer is interconnected with the PSTN and
130
by its own internal telecommunications modem
142
or other device. Like the panel, it is configured to place and receive calls over the PSTN, or to operate on a dedicated line to communicate with each panel.
The communication by the host with each panel is further described with reference to FIG.
2
. The monitoring station, via the host computer
140
continually checks the status of each alarm panel on its given list of subscribers generally in a round robin fashion. Typically, a post poll select function (
200
) is executed by the host computer for a selected panel. As such, a call or polling function reads the selected alarm panel (
202
) via the PSTN. In response to the poll select, the panel transmits a status signal (
204
). In general, the status signal includes various station/alarm panel address information as well as specific security system status data. For example, according to the ADT protocol, the digital number “03” indicates an “all clear” status. Other numbers may indicate a system malfunction or security breach. The protocol used to poll the panel, and to return status does not include an “address” or other identifier indicating the identity of the particular polling host. This is because direct calls over the PSTN are made to and from the alarm panel (e.g. the host's location is always known). The polling procedure shown in
FIG. 1
occurs in round robin sequence throughout a group of alarm panels until all panels have been polled, and responses have been received therefrom. This is an asynchronous process in which a poll occurs at the host, and a status response is sent by the alarm panel at a short, but indefinite, time thereafter. Once all alarm panels on the host's subscriber list have been polled, and status received, the polling process repeats itself.
As noted, the information transferred from each alarm panel does not include particular addresses about its destination (e.g. returning to the host). This limits the ability of such information to be transferred over a distributed network such as the well-known Internet where source and destination address information is needed to appropriate route data. For information to be effectively routed over the Internet, an Internet Protocol (IP) source and destination address is generally needed within the transmitted data stream or “packet.”
Accordingly, the object of this invention that provide a method and apparatus for enabling information that does not include source and destination addresses to be returned to a host from a remote source following a asynchronous polling of the source by the host for that information. This method and apparatus should enable the existing hosts and alarm panels (or other data devices) configured to operate free of IP layer addressing functions to be used without significant modification.
SUMMARY OF THE INVENTION
This invention overcomes the disadvantages of the prior art by providing a router system between a host and a set of alarm panels that enables routing of data therebetween over an Internet Protocol (IP) layer network when the data is originally adapted to be transferred asynchronously without network source and destination addresses, and more particularly without any identification of the polling host in the panel's response. This is accomplished by providing routers at the host side of the network and at the panel side of the network that each provide the required addresses and identifiers and append these addresses to data sent by both each host and each panel.
More particularly, a primary router is interconnected between a set of alarm panels and the IP network. Likewise, a secondary router is connected between one or more hosts and the IP network. In a typical polling operation, the secondary router identifies the particular host sending the polling signal. It then stores the host information, and based upon a panel address contained in the polling signal, appends an IP source and destination address to the polling signal. This source and destination address is developed based upon a prestored table within the secondary router that cross references the host protocol contained in the polling signal with a specific alarm panel connected to a specific primary router. The appended data packet is then transferred over the IP network to the primary router. The primary router receives the polling signal, and its protocol interface block stores the source and destination address of the secondary router from which the polling request came, and also stores a tunnel layer data segment containing the host's identity to later identify the polling host. The primary router then transmits the polling signal to the appropriate alarm panel (connected to the router via a port) based upon the station address contained within the protocol data of the packet. The poll generates an appropriate status response data code at the alarm panel. Note that this status response does not generally contain information about the identity of the polling host. This status response is returned to the primary router which, in turn, reappends a source and destination address (as network layer data) and the previously stored host identification data (as tunnel data). The protocol interface in the primary router then transmits the appended data packet back to the secondary router. At the secondary router the data is then stripped of addresses and forwarded to the host in a protocol form recognized by the host. In this manner, the host and alarm panel communicate with each other as if a direct telephone connection were in place, the netwo
Cesari and McKenna, L.L.P.
Cisco Technology Inc.
Lim Krisna
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